Headwear: warm hat, sun hat, neck gaiter

Head and neck have a good blood supply and are usually uncovered, while the rest of the body is in clothing. That is why you noticeably lose heat there when it is cold and windy, and easily get sunburnt there when the sun shines. A wool or synthetic hat holds a layer of still air that insulates. It is important that it covers the ears, because ears are thin and cool down quickly.

A sun hat works through shade instead. A wide brim all round protects face, ears and neck better than a cap that leaves the neck bare. A light-coloured, airy hat lets heat escape; a dark, close-fitting one traps it. A chin strap stops the wind from carrying the hat away.

The neck gaiter is an all-rounder between the two. You can wear it as a neck warmer, headband, thin hat or as a cloth over mouth and nose against wind and coarse dust. It weighs almost nothing and dries quickly.

Headwear is one of the fastest ways to control body warmth. When climbing you get warm – take the hat off before you start to sweat. As soon as you stop for a break, put it back on straight away, because the body then cools quickly. That way your clothing stays drier and you feel less cold.

A common mistake is leaving the hat at home because it is warm at the start. On the mountain, in the evening or when the weather changes it can quickly become much colder. A hat weighs so little that it really belongs on every trip. A wet hat, on the other hand, should not be kept on; swap it for a dry one or use the neck gaiter.

Make sure the hat fits under your hood and – if you wear one – under a helmet. A helmet protects against rockfall, when climbing or cycling; a hat can never replace it.

The World Health Organization (WHO) recommends a wide-brimmed hat when the UV index is raised – but together with shade, clothing, sunglasses and sunscreen. A hat alone is not enough, because UV radiation is also reflected by water, sand and especially snow and then reaches the face from below. In the mountains UV radiation is also stronger than in the lowlands.

Check the UV index in the weather forecast before your trip. Radiation is strongest around midday; that is when shade is especially valuable. Children need particularly good sun protection.

In heat an airy, light-coloured hat is better than a close-fitting cap. Headache, dizziness, nausea or great exhaustion can be signs of heat illness. Then get into the shade at once, rest, cool down and drink. If someone becomes confused or unconscious, call the local emergency number (112 in the EU).

On a summer hike in the mountains both kinds of headwear often belong in the pack: the sun hat for the day and the warm hat for the summit, the evening or a thunderstorm with cold wind. In winter the warm hat is a must, and the neck gaiter protects neck and face from icy wind.

If you have no sun hat, you can tuck a cloth under a cap so it hangs over your neck and ears. This is an old, proven solution from hot regions. More on this in the entry on improvised sun protection.

Headwear is easy to lose, especially in wind. A chin strap, a clip on the jacket or a fixed habit of where you stow the hat helps. A second thin hat or the neck gaiter make a good reserve.

You often hear that most body heat is lost through the head. That is not really true. The head loses roughly as much heat as its surface area suggests – not an unusually large amount. The reason a hat still helps so much is different: the head is often the only uncovered part of the body, and that is exactly where an extra layer helps immediately.

Mountaineering handbooks have therefore long listed a warm hat as basic gear, because it adds a great deal of comfort for very little weight. There are separate tests for how well a fabric protects against UV radiation; this entry gives no figures on that.